yeah, the n-th order effects like the siberian ice melting away into methane emissions equivalent to 100 years of 2020 CO2 output will just completely obliterate any efforts at mitigating new emissions.
1300 * 10^9 is about 100 years of 2020 CO2 activity.
13 * 10^6 is 100/1000 years of 2020 CO2 activity, I guess.
Did you mean to write "if it keeps speeding up"? Because it is most definitely happening, it is speeding up [1], and it doesn't look likely to slow down.
[1] https://earthobservatory.nasa.gov/images/146978/methane-emis...
The NASA article you linked is reputable, but pay attention to what it actually says - it makes no predictions of impact severity.
What the article DOES say: methane is responsible for 1/4 of all global warming, it's increased 9% in the last decade, and 250% in the last 17 decades (avg 15%/year).